fix travis and reduce warnings

quantum/audio/voices.c

@@ -24,6 +24,7 @@ void voice_deiterate() {
 
 float voice_envelope(float frequency) {
     // envelope_index ranges from 0 to 0xFFFF, which is preserved at 880.0 Hz
+    __attribute__ ((unused))
     uint16_t compensated_index = (uint16_t)((float)envelope_index * (880.0 / frequency));
 
     switch (voice) {

quantum/process_keycode/process_unicode_common.h

@@ -7,6 +7,7 @@
 #define UNICODE_TYPE_DELAY 10
 #endif
 
+__attribute__ ((unused))
 static uint8_t input_mode;
 
 void set_unicode_input_mode(uint8_t os_target);

util/travis_compiled_push.sh

@@ -7,7 +7,7 @@ rev=$(git rev-parse --short HEAD)
 git config --global user.name "Travis CI"
 git config --global user.email "jack.humb+travis.ci@gmail.com"
 
-if [[ "$TRAVIS_BRANCH" == "master" ]] && [[ "$TRAVIS_PULL_REQUEST" == "false"]] ; then
+if [[ "$TRAVIS_BRANCH" == "master" && "$TRAVIS_PULL_REQUEST" == "false" ]] ; then
 
 increment_version ()
 {